Welcome to the forum!
Yes, these are too easy for the Advanced ... but hey, if you don't know the anwser, how are you supposed to know that? Anyway, no harm done. If in doubt, the best thing to do is post in Editing/Scripting: General.
Anyway, to the answers. To do gear selection from the Briefing you need a little file called description.ext. There are tutes in the Editors Depot, but I suggest you d/l the
Tutorial Mission and borrow the one in there. You can edit it to suit your own mission. Look at the tutes too, of course, so you understand what is going on.
To make a mission end from a script finish your script like this:-
endMission=true
exit
Create a trigger:-
Type: End#1
Condition: endMission
when the variable endMission is set to true by the script, the trigger will fire and the mission will end.